As thousands of college students pour back into Boston for the start of another school year, Mayor Thomas M. Menino pledged to crack down on irresponsible landlords and renewed his support for tougher regulation of rental properties.

“We are going to make sure all the units meet all the requirements,” he said at a news conference on Ashford Street in Allston, a student-heavy neighborhood where city inspectors fanned out Friday in search of code violations. Some 70,000 people are moving into apartments this Labor Day weekend.

Menino also voiced support for a new city ordinance that requires landlords to register their apartments with the city and have them inspected every five years, saying the oversight will force landlords to clean up blighted properties and make tenants safer.

“We’re serious and we’re going to make it work,” Menino said.

Brian Swett, who oversees the city’s inspectional services department, said inspectors will be out in force this weekend to make sure apartments meet “basic health and safety standards.”

Currently, nearly all inspections are prompted by complaints, and many problems are not brought to the city’s attention. Officials point to the death of a Boston University student in an apartment fire this spring — an apartment that was overcrowded and hadn’t been inspected in years — as tragedies that can be avoided with better oversight.

David L. Ryan/Globe Staff

City inspectors fanned out in search of code violations by landlords on Friday.

In a letter to city councilors this week about the new ordinance, Swett said the fatal fire served as a “clarion reminder” of the importance of inspections.

Property owners have criticized the regulation as intrusive and costly, however, and have been slow to register their units with the city. Officials said they will not extend this week’s deadline, but said they are focusing on problem landlords and do not plan to assess fines broadly.

City officials said they have gotten a surge of registrations in recent days as more landlords learn about the program. The city has promoted the new ordinance aggressively in recent weeks, posting fliers and sending out notices, and officials said they expect much higher compliance when all the registrations are tallied.

“I think we’re going to get a big push in the end,” Glascock said.

Landlords must pay the city $25 per apartment as a registration fee. Many have chafed at the regulation and have urged city councilors to revisit the issue, with an eye on limiting the scope of the rules.

Many say they should not have to register every year and that inspectors should concentrate their efforts on landlords who fail to maintain their properties.

In the past, inspectors have visited buildings responding to reports of rodent infestations, trash violations, and safety hazards, including blocked exits and missing windows.

Speaking in front of a three-story apartment house that had been cited for previous code violations, city officials said they had seen improvements in student neighborhoods like Allston and the Fenway, and hoped to build upon those gains. Landlords who do not bring their properties up to code face substantial fines, officials said.

“We have a lot of confidence we’re heading in the right direction,” Glascock said.

Looking on, a few Allston residents said they supported the city’s efforts and hoped this batch of students wouldn’t make quite so much noise or stay up quite so late. But they weren’t all that hopeful.

“Police focus on the bars, so they can’t focus on the neighborhoods,” one neighbor said.

Swett said the registry would help city officials quickly get in touch with property owners and managers, a process that can otherwise prove time-consuming. Officials also plan to create a list of landlords who do not address violations.

“We’ll know how to reach them if there are problems,” he said.

City officials estimate there are 140,000 rental units in the city that are required to be registered. Two-thirds of the city’s housing is rental, and in neighborhoods like Allston and Mission Hill the percentage is much higher.